2. Learning Targets
⢠Identify common blood tests and their
purpose in diagnostics.
⢠Discuss lab skills, safety, and procedure.
3. Blood as a Diagnostic Tool
⢠Blood is often used as a diagnostic for several
reasons:
â Blood is easily accessible. It is relatively harmless
to obtain and low risk. It is also not expensive to
test blood.
â Blood can give us lots of information. It contains
cells and plasma, and gives a good general status
of the body function.
4. Limitations of Blood Tests
⢠Cannot be treated as absolutes in most cases,
due to margin of error.
â When we test blood we take only a small sample,
which should be representative, but is not always.
â Lurking variables can skew results.
â Issues in the central nervous system are hard to
see with blood tests due to blood brain barrier.
5. Lab Safety Basics
⢠Remember Standard Precautions
â Just because the patient is not standing their, you
should still observe all appropriate precautions with
body fluids.
⢠Be especially careful with transferring blood and
obtaining specimens.
â Higher risk for contamination.
⢠Sharps are common.
â Lots of needles are used and disposed in the lab
setting. Do it correctly.
6. Lab Skills
⢠Venipuncture â obtaining blood via a peripheral stick.
â This is adequate for most lab requests.
â Involves locating, accessing, and then de-accessing a vessel near
the peripheral surfaces of the skin.
⢠Arterial Puncture â obtaining blood from an artery.
â This is higher risk due to pressurized blood in these vessels.
â After care is especially important. Lack of appropriate care can
lead to bleeding or hematoma.
⢠Obtaining Blood from a Central Line
â This is a special skill, usually only performed by an RN.
â Proper technique and precautions use to high risk of infection.
7. What are those colored tubes about?
⢠They are called âVacutainersâ
â Test tubes used in the tests are voided of air, and therefor will
pull a specimen in, only until the appropriate amount is present.
⢠The color to indicates what type of additive is in the tube.
â Some tubes have enzymes that prevent clotting, cause
separation of blood parts, etc.
â This is needed depending on the different test to be run.
⢠Draw order:
â It does matter what order tubes are drawn in.
â Some tests need to be drain first, others should have blood
wasted (or used in other tests) before hand.
8.
9. Blood Components
⢠When we test blood, we have several factors to
look at:
â Plasma, which contains lots of solutes (hormones,
nutrient levels, sugar, waste products, electrolytes,
chemical factors etc.)
â Red Blood Cells (which we can count, test for reaction
properties, shape, etc.)
â Platelets (tell us about blood clotting)
â White blood cells (there are many types, and different
levels of each can indicate disease or infection)
12. A Closer Look at Blood Components
Red Blood Cells
⢠We can look at the
shape/size of the cells, the
number of cells or even
specific chemical factors
about the cells to give us
information about the body.
⢠The normal range for RBC is:
4.2 to 6.1 million per
microliter.
Hemoglobin
⢠This usually corresponds to
RBC, but is specifically is the
oxygen carrying molecules
in the cell.
⢠Normal range: 12-18 grams
per deciliter.
⢠In both of these, men tend
to run higher than women.
13. A Closer Look at Blood Components
Albumin
⢠Albumin is the prime
protein in blood, and
creates the appropriate
level of osmotic pressure to
prevent loss of excess blood
into the tissues.
⢠Low levels can indicate liver
disease or starvation.
Platelets
⢠Platelets are a key part of
the clotting cascade. They
are cell fragments made
from special bone marrow
cells.
⢠These cells must work
together with the various
clotting factors to stop
bleeding when it occurs.
14. White Blood Cells
Elevated Total WBCs
⢠This is a count of all white
blood cells (5 types).
Further more specific
counts may be used to
figure out specific
problems.
⢠Increased levels indicate
stress, or infection.
Decreased levels indicate
immune suppression.
Elevated Individual Types of
WBCs
⢠Certain types of WBCs
respond to different needs
in the body.
â Elevated Eosinophils may
indicate a parasite infection
or allergic reaction.
â Immature white blood cells
indicate a serious systemic
infection called sepsis.
â Decreased levels of Killer T
Cells indicates advancing HIV
15. Common Blood Tests: The Blood Count
(CBC)
⢠A complete blood count (CBC) is a blood test used to evaluate your
overall health and detect a wide range of disorders, including
anemia, infection and leukemia.
⢠A complete blood count test measures several components and
features of your blood, including:
â Red blood cells, which carry oxygen
â White blood cells, which fight infection
â Hemoglobin, the oxygen-carrying protein in red blood cells
â Hematocrit, the proportion of red blood cells to the fluid component,
or plasma, in your blood
â Platelets, which help with blood clotting
⢠Abnormal increases or decreases in cell counts as revealed in a
complete blood count may indicate that you have an underlying
medical condition that calls for further evaluation.
16. Common Blood Tests: BMP and CMP
CMP â gives basic blood chem, plus information
about liver and kidney function.
⢠Albumin â blood protein
⢠Alkaline Phosphatase â liver test
⢠ALT - liver test
⢠AST - liver test
⢠BUN â kidney function indicator
⢠Creatinine â kidney function test
⢠Calcium
⢠Chloride
⢠Carbon Dioxide
⢠Glucose
⢠Potassium
⢠Sodium
⢠Serum Bilirubin
⢠Total Protein
BMP â gives a basic picture of blood
chem, plus kidney function.
⢠BUN â Blood Urea Nitrogen
⢠Creatinine
⢠CO2
⢠Glucose
⢠Chloride
⢠Potassium
⢠Sodium
17. Common Blood Tests: ANA and ESR
ESR â Erythrocyte Sedimentation
Rate
⢠Literally measures o how
fast the RBCs sink to the
bottom of the tube.
⢠Faster Rates occur in
diseases that result in
systemic inflammation
(autoimmunity issues
especially)
ANA â Antinuclear Antibody
⢠This test measures the
presence of antibodies in
the blood that are targeted
at the bodyâs own tissues.
⢠These rates are elevated in
autoimmune issues, liver
disease and inflammatory
issues.
18. Common Blood Tests: Coombâs Test
⢠This test measures antibodies that are in the
blood (indirect) or are bound to the red blood
cells (direct).
â Elevated levels may occur in reactions to
transfusion, infectious disease, autoimmune
disease.
19. Common Blood Tests: Liver Function
Tests
⢠Measures of several blood components can give
indication to liver function:
â ALP
â AST/ALT
â Bilirubin
⢠These markers and enzymes indicate either
directly or indirectly damage to the liver.
⢠Liver disease may also result in elevated
inflammation markers, low blood counts or blood
protein.
20. Common Blood Tests: Kidney Function
⢠Tests that monitor the function of the kidneys
mainly rely on measuring levels of waste
product in the blood. As levels rise, it
indicated the kidneys are not working.
â BUN
â Creatinine
⢠Other indicators of kidney issues can be found
in urine, or be expressed as electrolyte
imbalance or anemia.
21. Common Blood Tests: Blood Culture
⢠If a septic infection is suspected (an infection
which is spreading in the blood), blood
cultures can be performed.
â Just like cultures of wounds or other fluids, blood
is obtained and allowed to âgrow outâ on a
medium.
â Then, any growth is tested as to what it is and
what medication is effective.
22.
23. Common Blood Tests: Blood Clotting
Studies
⢠Other than the number of platelets present,
several other measures can be made concerning
how long it takes the blood to clot. This can be
used to identify a problem or to see if medication
meant to slow clotting is effective.
â INR: international normalized ratio is a measure of
how long it takes certain factors to begin working in
the clotting cascade. It is used to monitor medication
levels.
â PT/PTT â measures how long it takes for Prothrombin
and thrombin to activate in the clotting cascade.